I. Field of the Invention
This invention relates to a pulsed alternator which can deliver high energy pulsed current in response to rotational movement of a rotor through a magnetic field. In particular, the present invention comprises armature coils stacked on the outer periphery of the rotor and symmetrically arranged with respect to one another to balance forces along the longitudinal axis of the rotor when current is discharged through the coils.
II. Description of the Relevant Art
There are many applications that require a high energy pulsed power source which can deliver extremely high power within a relatively short time period. Electrostatic capacitors are typically used to deliver high energy across a low impedance load. Electrostatic capacitors are, however, fairly expensive to manufacture and cannot achieve energy storage per unit mass adequate for certain types of load such as, e.g., mobile, vehicle mounted electromagnetic railguns.
In hopes of providing high energy output necessary for railgun operation (i.e., pulsed output exceeding one million amps), research has produced homopolar generators. While homopolar generators can produce fairly high current within a fairly short discharge time, homopolar generators are relatively low voltage devices, making them unsuitable for higher impedance loads. Conversely, pulsed alternators have been developed which can produce the necessary voltage or power but have numerous shortcomings, such as high internal impedance.
Conventional alternators utilize windings placed circumferentially upon the outer surface of a rotor. Conventional windings utilize a single layer of coiled conductors arranged in a generally non-symmetrical fashion about the rotor's outer surface. Non-symmetrical, conventional windings thereby experience excessive lateral force upon the rotor during very high current discharge. When the single layer, non-symmetrical coil discharges extremely large currents an imbalanced Lorentz force is created along the longitudinal axis of the rotor. The imbalance becomes so severe that bearings and seals quickly wear out or fail during discharge. Thus, conventional pulsed alternators suffer excessive mechanical wear whenever extremely high pulsed current is discharged. Still further, conventional alternators utilize heavy ferromagnetic or non-ferromagnetic materials within their rotor and surrounding stator. These materials add excessive weight causing depletion in alternator output performance; i.e., reduction in energy density and power density output.